Tagging and tracking of products and devices utilizing radio frequency identification (“RFID”) is widely used in manufacturing and packaging processes, but has not been used to label implantable medical devices.
As described by the Association for Automatic Identification and Mobility of Warrendale, Pa. (“AIM”), a basic RFID system consists of three components: an antenna or coil; a transceiver (with decoder); and a transponder (RF tag) electronically programmed with unique information. The electromagnetic field produced by the antenna can be constantly present when multiple tags are expected continually. If constant interrogation is not required, the field can be activated by a sensor device.
Often the antenna is packaged with the transceiver and decoder to become a reader or interrogator, which can be configured either as a handheld or a fixed-mount device. The reader emits radio waves in ranges of anywhere from one inch to 100 feet or more, depending upon its power output and the radio frequency used. When a RFID tag passes through the electromagnetic zone, it detects the reader's activation signal. The reader decodes the data encoded in the tag's integrated circuit (typically a silicon chip) and the data is passed to the host computer for processing.
AIM further describes RFID tags as available in a wide variety of shapes and sizes. Tags can be as small as a pencil lead in diameter and one-half inch in length. Thus, an RFID tag of this size is suitable as a component of an implantable medical device.
According to AIM, RFID tags are categorized as either active or passive. Active RFID tags are powered by an internal battery and are typically read/write, i.e., tag data can be rewritten and/or modified. An active tag's memory size varies according to application requirements; some systems operate with up to 1 MB of memory. In a typical read/write RFID work-in-process system, a tag might give a machine a set of instructions, and the machine would then report its performance to the tag. This encoded data would then become part of the tagged part's history. The battery-supplied power of an active tag generally gives it a longer read range. The trade off is greater size, greater cost, and an operational life limited to about 10 years depending on operating temperatures and battery type. However, such an operational lifespan is well suited for an active tag included with an implantable medical device.
Passive RFID tags operate without an internal power source and obtain operating power that is generated by the reader. Consequently, passive tags are much lighter than active tags, less expensive, and offer a virtually unlimited operational lifetime. The trade off is that they have shorter read ranges than active tags and require a higher-powered reader. Read-only tags are typically passive and are programmed with a unique set of data (usually 32 to 128 bits) that cannot be modified.
AIM reports that the significant advantage of all types of RFID systems is the non-contact, non-line-of-sight nature of the technology. Tags can be read through a variety of substances, including human tissue, where barcodes or other, traditional optically read technologies would be useless. RFID tags can also be read in challenging circumstances at remarkable speeds, in most cases responding in less than 100 milliseconds. The read/write capability of an active RFID system is also a significant advantage in interactive applications such as work-in-process or product tracking.
Although RFID is a costlier technology (compared to barcode systems), it has become indispensable for a wide range of automated data collection and identification applications that would not be possible otherwise.
Current medical device configurations for implanted pulse generators, such as pacemakers or defibrillators, store ID's in a microprocessor memory and use custom communication protocols in an external programmer to extract the information. To accomplish their therapeutic purpose, such devices deliver timed sequences of low energy electrical stimuli, called pace pulses, to the heart. Such stimuli are delivered via an intravascular lead wire or catheter (referred to as a “lead”) having one or more electrodes disposed in or about the heart.
However, pulse generators with extractable identification information may not identify the manufacturer or type of the lead that is connected to the implantable medical device (“IMD”) in the case where the lead has been replaced in a patient. In addition, a custom communication protocol may not be compatible with components from different manufacturers. It is often the case that an original pulse generator lead, for example, is replaced with a lead from a different manufacturer. So, even if the manufacturer's pulse generator could identify the original manufacturer's lead, the manufacturer's custom communication protocol would typically fail to recognize the replacement lead. However, if IMD manufacturers adopt an industry-wide communication protocol, that would solve the problem of component identification and allow for confident interchangeability of component parts. There is a need for an industry-wide communications protocol that allows for IMD and associated implanted component identification. Such a communications protocol would provide IMD and associated implanted component manufactures confidence in using IMD associated components interchangeably.
Devices such as leads and stents do not currently have an electronic mechanism for identification of their model/serial number, and manufacturing information. Most often, X-rays are the most common approach to identifying such devices. In addition, leads and stents typically do not have their own power sources. There is a need for leads, stents and other IMD components to have electronic mechanisms for identification. Such identification mechanisms would simplify the identification of a particular model or associated serial number of such devices along with other specific information about the device and/or its component parts.
Leads, stents and other IMD components that have electronic mechanisms for identification would be used in combination with IMDs and a system that provides for identification and tagging of specific medical devices and the identification of patients using such devices to automatically and quickly identify manufacturing information about the devices, their component parts and the recipients of such devices. Such a system will improve the manufacturer's and the clinician's ability to manage and monitor the devices while in clinical use.